The customer account code was divided into subgroups: four digits for the bank code (coinciding with the Bank of Spain's Entities Registration Number, NRBE); another four for the code of the branch where the account was opened; two check digits used to validate the customer account number; and ten digits to identify the account number.
Before the Customer Account Code there was the Bank Identification Number, standardised in 1979 to identify current credit and savings accounts; in fact, this code took on the same structure. And in turn, globalisation and the extension of financial transactions beyond our borders has made it necessary to issue agile and secure cross-border payments. That is why it was replaced by the IBAN code (International Bank Account Number), and in fact it is an evolution of it.
The IBAN is a common alphanumeric code established by the European Banking Standards Committee, to standardise and unify the account system of European banks. All the countries belonging to the single euro payments area (SEPA) share this IBAN; it ensures a standardised and correct data transmission. Although each country has a different number of digits (for example, in Malta there are 30, and in Belgium 12), this code has facilitated the management of trade and transfer operations within the European Union.
In Spain we operate with 24 digits, distributed as follows: the initial two letters ES, correspond to Spanish accounts; then two check digits; four for the bank code; another four for the code of the branch where the account was opened; two corresponding to a validation code (a mathematical algorithm); and finally, ten digits corresponding to the account number.